Vertical gun-puffing apparatus



VERTICAL GUN-PUFFING APPARATUS Original Filed Jan. 21, 1958 FIG. 1.

5 Sheets-Sheet l INVENTORS l5 JAMEs V. GRAHAM GORDON A. GOODRICH RocmnB. MILLER d rnmwzl, Mam

ATTORNEYS June 18, 1963 J. v. GRAHAM ETAL 3,094,059

VERTICAL GUN-PUFFING APPARATUS Original Filed Jan. 21, 1958 5Sheets-Sheet 2 7 INVENTORS JAMES V. GRAHAM GORDON A GOO'DRICH ROGER B.MILLER June 18, 1963 VERTICAL 'ori inal mled Jan. 21, 1958 F I G. 3. ML:

GRAHAM ETAL GUN-PUFFING APPARATUS 5 Sheets-Sheet a 8 84 2 as INVENTORS-JAME5 V. GRAHAM GORDON A.GOODRICH ROGER. B MILLER. ah mum, mid/mATTORNEYS June 18, 1963 J. v. GRAHAM ET AL VERTICAL GUN-PUFFINGAPPARATUS Original Filed Jan. 21", 1958 5 She ets-Sheet 4' m: K om hzuEwz NP 0W I INVENTORS 5 JAMES GQAH GORDON A.GooDR1cH. Y ROGER B.M1LLR.Gammon, ATTORNEYS Wm WW N. U H H Know June 18, 1963 J. v. GRAHAM ET ALVERTICAL GUN-PUFFING APPARATUS Original Filed Jan. 21", 1958 5Shets-Sheet 4 m 1 M3? fim XEM a? mi 8 JGR,

J n 3, 1963 J.- v. GRAHAM ETAL 3,094,059

VERTICAL GUN-PUFFINGAPPARATUS Original Filed Jan. 21, 1958 5Sheets-Sheet 5 FIG.8.

INVENTORS JAM E5 V. GRAHAM FIG.9.

GORDON A .GOODRICH ROGER B.M1LLER. W,

ATTORNEYS" United States Patent 9 Claims. (Cl. 99-238) This inventionrelates to cereal puflin'g apparatus and rnor particularly to improvedpufiing apparatus which is simple and inexpensive and at the same timeautomatic and substantially continuous in operation and capable ofproducing a uniformly puifed product of high quality.

The conventional method of putting cereal grains, dough pellets, andother cereal forms has been to charge the cereal forms or elements intoa closed pressure chamber or so-called gun wherein they are subjected topressure, together with heat and moisture when cooking as well aspuffing is desired. Usually steam is admitted to the closed chamber,after which a gate or door is unlatched and blown open practicallyinstantaneously by the pressure in the gun. The cereal elementsthereupon explode from the gun into a zone of lower pressure (usuallyatmospheric) and are pufied. This traditional practice is essentially abatch operation and .for large scale production resort has been made tothe use of a plurality of guns operating with overlapping cycles offilling, closing, pressurizing and opening or pufiing. In an effort tominimize manual labor and also to promote uniformity, US. Patent No.2,598,242 proposes auto matic mechanism set into action by the operatorafter the gun is charged for carrying out the subsequent operations ofclosing the gun, steaming and pressurizing the charge, and opening thegun to explode the charge.

Apart from the fact that the above procedure has the usual disadvantagesof a batch operation, it also produces non-uniform results with respectto the size and other characteristics of the puffed grains, pellets, orother cereal forms all hereinafter referred to as grains). The grainsare very sensitive to the time of their exposure to the high temperatureand pressure in the gun, to the amount to drop in pressure which theyundergo on opening of the gun, and to the rapidity with which this dropin pressure takes'place. These conditions can be controlled with respectto the batch as a Whole, but it is difficult if not impossible to avoidsubstantial variations in the treatment of the individual grains of sucha batch and especially in the rapidity of the drop in pressure in theindividual grains as they are expelled from the gun. Control of theseconditions with respect to individual grains becomes more difiicult asthe sizes of the gun and the batch are increased, whereas on the otherhand a large number of small batches is obviously undesirable forquantity production.

In an efiort to minimize these defects, it has been proposed to heat acharge of grain in a pressure container, and then to open a relativelysmall discharge outlet so that the pressure is retained in the containerand forces a mass of grain into the outlet through which the individualgrains of the mass are progressively expelled; see for example FergusonPatent No. 1,839,917. In this -method, however, the'time of exposureofthe individual grains to the hightemperature and pressure in thecontainer varies substantially because of the time required to expel theentire charge through the restricted outlet, and as a consequence thepuffed grains vary not only in size but also in degree of cooking.Moreover, forcing the mass of grain into and through the outlet tends tocause clogging of the outlet with resulting physical distortion andmechanical damage to many of the grains,

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and with the further result that some grains are held up in passingthrough the outlet so that the pressure drop therein takes placegradually. Another expedient pro posed to combat the same problem is theuse of an auxiliary steam chamber at the end of the gun opposite thegate through which the charge is expelled, as disclosed in Warren PatentNo. 2,261,456. This expedient avoids the diiiiculty of jamming of thecereal elements in a restricted orifice, but does not produce thedesired results as to uniformity of pressure drop in the individualgrains.

The prior practices described above are all essentially batch processes.A truly continuous process is disclosed in U.S. Patent No. 2,622,985,and this process solves the difficulty of non-uniformity and avoidsphysical distortion of the cereal elements, but is not feasible for useunder all conditions and with all types of cereal forms.

One of the objects of the present invention is to provide novel meansfor accomplishing substantially the results of the aforesaid priorPatent No. 2,622,985, as to quality of the product obtained, which meansalthough not truly continuous, is fully automatic in operation like theprocess of said prior patent but utilizes simpler and less expensiveequipment and is applicable generally to gun-putting operationsheretofore practiced.

Another object is to provide novel means as characterized in thepreceding object which, while not truly continuous as in Patent No.2,622,985, nevertheless operates automatically and without any manualintervention to repeat its cycle and thus to discharge a steady,uninterrupted succession of puffed batches at regular timed intervals.

Still another object is to eliminate the use of restricted orifices andyet to provide a less sudden drop of pressure in the gun than takesplace with latch-controlled pressure-operated gates of the usual type,with the result of promoting uniformity of puffing throughout an entirebatch.

The above objects and others will appear more fully hereinafter as thedescription proceeds.

In apparatus embodying the invention, it is preferable to employ apreheating stage prior to the pressurizing stage, since preheating canbe accomplished readily in Warm air or the like at atmospheric pressure,and the size of the equipment required to be capable of with standingpressure is greatly reduced for a given volume of production. Also itappears that preheating inwarm air before pressurizi-n-g with steam,and/or the temperin-g elfect incident to such preheating, contributes tothe high yield and quality of the pufied product. But since preheatingin warm air is apt to require more time than the subsequent steamingtime for the preheated change, it may be desired to employ twoalternately discharged preheating chambers with each pressurizingchamber.

The accomplishment of the objectives of the invention is furtherfacilitated if the preheated charge passes from the preheating apparatusthrough the pressurizing chamber and to the final collection or storagepoint in a straight, vertical, downward path. The vertically downwarddirection of movement of the charge makes it possible to move the chargeby gravity, with elimination of moving conveyor-type equipment, and alsomakes it possible to move the charge from one zone to another not onlyautomatically but also ivory rapidly. This is advantageous in theinterest of maximum utilization of equipment, conservation of preheatand moisture in the grains, and avoidance of losses incident to transferof the charge from one point to another by' conventional conveyingmeans.

It will be seen also that instead of a gun which is filled through agate or door at one point or end and which explosively opens the gateand discharges through it practically instantaneously, theuni-directional movement of the charge in the present invention requiresa vertical approximately tubular pulfing chamber arranged for thestraight-through passage of the preheated charge, the pressure zonebeing defined by an inlet valve at one end and an outlet valve at theother. For automatic operation in timed sequence, moreover, these valvesmust be power-operated instead of being merely unlatched to be blown:open by the explosive force of the steam pressure. It has been foundthat this arrangement has the added and unexpected advantage ofcontributing materially to uniformity of puffin-g. This may be due inpart to the fact that the opening of the discharge valve, while rapid,still takes place gradually as compared with the instantaneous explosionof the conventional gun, and thus exerts a measure of control of thepressure drop; yet it opens rapidly enough and far enough to avoid theadverse physical effects of throttling mentioned above. On the otherhand, the vertical pressure chamber and its bottom discharge permit thewhole charge to pass rapidly out of the gun with a minimum of dangerthat some parts of the charge may be retarded materially relative to theremainder with possible resulting localized overcooking and non-uniformpuffing efiects.

It will be seen that the automatic operation of a system of the typediscussed requires thned control and mechanical operation of a pluralityof valve means for the preheater, for eifecting the movement of thecharge from the preheater to the pressurizing chamber and the openingand closing of the inlet and outlet of the chamber, and for supplyingpressurizing fluid such as steam to the chamber. Various types of timedvalve control systems are known which are actuated electrically,hydraulically, and/ or pneumatically, and any such system is within thebroad purview of the invention. It is preferred, however, to employpneumatic valve actuators, the air supply being regulated by pneumaticpilot valves operated by a suitable timer device as describedhereinafter.

One embodiment of the invention has been illustrated in the accompanyingdrawings but it is to be understood that said drawings are for purposesof illustration "only and are not to be construed as a definition of thelimits of the invention, reference being had to the appended claims forthis purpose.

In said drawings,

FIG. 1 is an elevation, partly in section, of apparatus embodying theinvention;

FIG. 2 is an elevation of the apparatus of FIG. 1, taken at right anglesto FIG. 1;

FIGS. 3, 4 and 5 are respectively top, front and end views of thepreheating apparatus which forms part of FIGS. 1 and 2;

FIG. 6 is a diagrammatic view illustrating the control system employedfor the automatic operation of the apparatus;

FIG. 7 is a detail of certain elements employed in. the control system;and

FIGS. 8 and 9 are sectional views taken at right angles and showing onesuitable type of control valve for the pressurizing or pulling chambers.

It will be convenient first to describe the system as a whole withparticular reference to diagrammatic FIG. 6, before going into detail asto the specific structure of the units of the system. The main elementsof the system are indicated generally in FIG. 1 and comprise at the topa main feed hopper 1 having a pair of tapering bottom outlets ordownspouts 2 and 3 for delivery of material into the opposite ends of adouble-ended preheater unit 4. Warm air is supplied to the two ends ofthe preheater unit through conduits 5 and 6 which are in turn suppliedby pipe lines 7 and 8 (shown in dot and dash lines in FIG. 6) leading toa common source such as a suitable blower 9. The blower in turn issupplied with warm air by a suitable heating chamber 10 and the exhaustfrom the preheater 4 is returned to this heating 4 chamber through aline 11 (also indicated in dot and dash lines in FIG. 6).

The preheater 4, here shown as a double unit, is provided with twinbottom discharge conduits or downspouts 12, 13 which merge and deliverthe preheated charge into the upper end of a pressurizing chamber unitindicated as a whole by the numeral 14. The puffed cereal charge isdischarged from the unit 14 into any suitable receiver 15.

The system described generally above is operated automatically by ninepower-operated valves which for convenience are numbered consecutivelyas follows:

Two warm air inlet valves 16 and 17 in the warm air conduits 5, 6 to thepreheater 4, these valves as shown being of the butterfly type; twopreheater inlet valves 18, 19, preferably simple slide valves, onebetween, each preheating chamber and the respective downspout 2 or 3 ofthe hopper 1; two preheater outlet valves 20, 21, prefenahly simpleslide valves, one between each preheating chamber and the respectivedischarge conduit or downspout 12 or 13 leading to the pressurizing unit'14; an inlet valve at the top of the pressurizing unit 14 which isindicated generally at 22; a discharge valve at the bottom of thepressurizin-g unit which is indicated generally at 23; and finally asteam control valve 24 in the steam supply line 25.

The preheater 4 is shown as being of the double chamber type for reasonsstated above. It will be understood that if only a single preheatingchamber is desired, then one of the air control valves 16 or 17, one ofthe slide valves 18 or 19, and one of the slide valves 20 or 21 would beunnecessary. In the case of a single preheating chamber, moreover, bothslide valves 26 and 21 could be omitted in some cases since the inletvalve 22 of the pressurizing unit would be sufiicient.

Each of the nine valves is operated automatically by a suitablepneumatic cylinder and piston, there being accordingly ninedouble-acting cylinders numbered 26-34 to correspond with the linevalves 16-24. These nine cylinders are indicated diagrammatically inFIG. 6. In the case of the reciprocating slide valves such as 18, 19,they may be connected directly with the valve elements. Where necessary,on the other hand, cylinders are connected to valves through suitablelinkages, as in the case of the steam supply valve 24 which is connectedwith its operating cylinder 34 by means of the operating arm 35. Similaroperating arms 35 are provided for the butterfly valves 16 and 17.

Each cylinder is double acting, having a fluid pressure line from eachend to a suitable associated pilot valve, the nine pilot valves beingnumbered 36-44 and corresponding respectively with the nine valves 16-24and cylinders 2644. The pilot valves control the admission of fluidpressure to one or the other end of their respective cylinders accordingto the position of the valve element described hereinafter. The positionof this valve element is in turn regulated by a connection from eachpilot valve to a timer control unit 45, the nine individual connectionsbeing numbered 4654. A common low pressure air supply line is branchedat 56 and the nine branches supply low pressure air to nine pilot valvecontrol units located in the top of the timer control box. These controlunits are actuated by cam-like devices 57 arranged in a row on a commonshaft and indicated in dotted lines in FIG. 6, the shaft being driven bya motor 58 and suitable gearing housed in the gear box 59'.

FIG. 7 shows a suitable type of pilot valve control unit 60 inassociation with a suitable pilot valve, for example, the pilot valve 36which controls the cylinder 26 and the air supply valve 16. The lowpressure air from one of the branches 56 of the supply line 55 isadmitted to the chamber 61 at the top of the control unit 60 and whenthe ball valve 62 is open as shown in FIG. 7, this low pressure airpasses out through the passage 63 and through the line 46 to the top ofthe pilot valve 36, where it enters a diaphragm chamber 64 and depressesa diaphragm 65. The diaphragm stem 66 carries a ball valve 67 and isnormally urged upwardly against the air pressure by a suitable spring68. With the ball valve 67 in its down position as shown, high pressureair enters the pilot valve casing through a passage 69 and leaves thevalve casing through passage 70' connected to the appropriate end of thecylinder 26. As the time control shaft rotates, the appropriate camlikeelement 57 thereon eventually engages the bottom projecting end 71 ofthe ball valve 62 in the control unit and lifts this valve to its upperposition, thus shut ting off the supply of low pressure air to thediaphragm chamber 64. As long as the control unit valve 62 remains inthis raised position, the spring 68 is effective to hold the ball valve67 of the pilot valve in its upper position so that the high pressure.air coming from the inlet pas-' sage 69 leaves the valve casing througha passage 72 leading to the opposite end of the cylinder 26. Thus theoperation of the cylinder is reversed to shift the position of the valve16, which is held in shifted position until the ball valve 62 of thecontrol unit drops to its lowermost position and the diaphragm 65 isagain depressed as described above.

The operating cycle of the system can be described most convenientlywith reference to FIGS. 6 and 7.

Assume as a starting point the condition existing just prior to thedischarge of [a cereal charge from the pressurizing unit 5. Bothpreheater chambers will be in use, the slide or gate valves 18, 19, 20and 21 all being closed and the warm air valves 16 and 17 being open.Inlet and outlet valves 22, 23 of the pressurizing unit will both beclosed :and the steam supply valve 24 will be open.

When the pressurizing and/ or cooking interval is completed, or priorthereto when suflicient steam is supplied, valve 24 closes throughoperation of its pilot valve 44 and reversal of the pistol in thecylinder 34 as described above. Valve 53 then opens and the cerealcharge is puffed and discharged into the receiver 15.

Outlet valve 23 then closes, and inlet valve 22 and one of the slidevalves 20, 21, say 20, open to permit the preheated change in one ofthe'pneheating chambers to' drop by gravity into the pressurizing device14. At the same time one of the warm air valves 16, 17 closes, in thiscase the valve 16. 1

As soon as the fresh charge has passed into the pressurizing device, itsinlet valve 22 closes and the steam begin another preheating operation,all of the parts being now back intthe condition assumed as a startingpoint' This cycle continues to repeat automatically except that the twopreheating chambers are discharged alternately,- the time provided forpreheating being thus twice that provided for the pressurizing and/ orcooking cycle.

FIGS. 3, 4 and show the detailsof a preferred form ofthe doublepreheater which is indicated genenally at.

4' FIG. 6. The casing of the preheater is generally hexagonal incross-section but not a regular hexagon for reasons that will appearlater, and is disposed on a horizontal axis. It comprises top and bottomhorizontal walls 73, 74, an upper pair of outwardly diverging walls 75,and a lower pair of inwardly. converging walls 76.

The ends of the casing are suitably tapered down to and merged withconduits Sand 6 mentioned above, as shown at 77.

At each end of the preheater, a preheating zone is I formed by a pair ofsubstantially vertical parallel partitions which define a preheatingzone between them and are perforated for the passage of preheating airfrom conduits 5 and 6 through the zones. As indicated particularly inFIG. 4, these vertical partitions may comprise screens 78 extendingacross the casing of the preheating unit in spaced relation. The centralpart of the preheater unit between the two preheating zones forms anexhaust chamber to which the exhaust conduit '11 is connected.

The space between the screens 78 of each pair is left open at the topand bottom of the casing for the width of the top and bottom Walls 73,74 so as to provide inlet and discharge openings for the cereal chargeto be pulled, these openings being controlled by the slide valves 18,19, 20 and 21 described above. As shown in FIGS. 4 and 5, the downspouts2 and 3 from the hopper 1 preferably terminate in ends that conform insize and shape to the inlet openings at the top of the two preheatingzones. The slide valves 18 and 19 which control the inlet of the cerealelements to these zones may suitably comprise simple sliding plates 18and 19 which slide horizontally in retaining guideways 79 mounted in anysuitable mannor on the top wall 73 of the prehe-ater casing. Theseslides 18 and 19 are operated by the cylinders 28 and 29 mentionedabove, the cylinders being suitably mounted in front of the casing onframes 80 which may be used to support the preheater unit as describedhereinafter. The piston rods 81 of the cylinders 28 and 29 can beconnected to their respective slides 18 and 19 in any suitable manner,as by means of coupling devices 82 of any suitable type. Preferably thedischarge valves 20 and 21 also comprise sliding plates similar to thevalve plates 18 and 19 and are slidable in retaining guideways 83mounted on the bottom wall 74, the valve plates being connected bysuitable couplings 84 with the piston rods 85 of the operating cylinders30, 31 which may also be mounted on the frames 80 mentioned above.

As shown more particularly in FIG. 5, the bottom walls 76 of thepreheating zone are inclined downwardly and inwardly to the edges of thedischarge opening at the bottom of each zone. Preferably the angle thatthese inclined Walls make with the horizontal is greater than the angleof repose of the preheated cereal elements, so that although thegreatest width of the zones is much more than that of the dischargeopenings to provide greater capacity, yet when a bottom discharge valve20 or 21 is opened the preheated charge passes out of theinstantaneously when a discharge valve 20 or 21 is opened. p p

The details of a suitable pressurizing or puffing unit 14 are shown inFIGS. 1 and 2. section 86 having a flanged connection at its upper endto an end section 87 and at its lower end to a similar end section 88.These sections provide -a substantially restrict the free flow bygravity of the cereal charge into, This desired result of through, andout of the device. course further requires the use of valves of a typewhich move to wide open positions in which the valve openings are ofsubstantiallythe same diameter as the passages 90.

The preheated cereal charge coming from the downspout 12 or 13 can beconducted into the upper endof the pressurizing unit 14 in any desiredmanner. As stated above, the downspouts 12 and 13 preferably merge andas shown in FIG. 1,-the merged lower end of these downspouts is disposedabove :a hopper 91 through which the charge passes into the passage 90of the valve casing It comprises a central 22. The pressurizing fluidsuch as steam can be admitted to the chamber 89 in any desired mannerand as shown the supply pipe 25 referred to above is coupled to an inletnipple 92 on one side of the upper casing section 87 of the pressurizingdevice.

Any suitable means may be employed for mounting the apparatus discussedabove in the desired superposed positions. As shown in FIG. 1, forexample, the pressurizing device 86, 87, 88 is mounted in frameworkcomprising standards 93 rising from the floor 94. This fioor alsosupports the base of the blower 9 and heating chamber 10. Additionalstandards 96 rise from the floor to a point above the pressurizingdevice, where they are connected to the frames 80 mentioned above whichare suitably connected to and support the preheater unit.

As already stated, the inlet and outlet valves 22 and 23 of thepressurizing device must be power operated and are preferably such as tobe moved progressively and rapidly from fully closed position to thefully open position described above by a single stroke of theirrespective operating pistons. Subject to these requirements, however,any desired type of valve can be employed such as known gate andplug-type valves. FIGS. 8 and 9 show by way of example a known type ofplug valve that has given good results. The valve casing 22 (or 23) istraversed by the straight passage 90 mentioned above, which is closed bya tapered plug 97 seated in the casing and rotatable by means of a stem98. The plug has a bore 99 adapted to align with the passage 90 when theplug is rotated and having substantially the same diameter as thepassage 90.

The valve plug is rotated by a suitable double-acting pneumatic cylinderas diagrammatically indicated at 32 in FIG. 6. As shown moreparticularly in FIGS. 7 and 8, this cylinder may be divided into twochambers 100 each containing a piston 101, the two pistons beingconnected by a rod 102 so that they operate as a unit. When the pistonassembly 101, 102 moves in either direction, rack teeth formed on oneside of the rod 102 mesh with the teeth of a gear 103 carried by thestem 93 of the valve plug 97. Thus the movement of the piston assembly101, 102 in one direction rotates the valve plug 07 to open position,and the movement of the piston assembly in the opposite directionreturns the valve plug 97 to closed position.

If desired, provision can also be made for manual operation 'of thevalve plug 97 in case of need. For example, the rod 102 may also beprovided with teeth on another side which mesh with a pinion 104 on astub shaft 105 that carries a worm wheel 106 driven by a hand wheel 107in any suitable manner. Other structural details of this valve aretypical and need not be described in detail. The casing 22 is closed bya bonnet 108 and packing gland 109. The cylinders and operatingmechanism are carried by a secondary casing 110, .111, the casing part111 having suitable bracket extensions 112, etc., whereby it is mountedon the valve bonnet 108. The casing 110', 111 is suitably arranged toprovide the necessary bearings for the ends of the valve stem 98 andstub shaft 105 and for the reciprocating rod 102; and to carry theopera-ting cylinder sections. These details are known and are not partof the invention, and hence will not be further described.

The operation of the system has already been described with reference toFIGS. 6 and 7. The timing of the various operations will of course varyaccording to the purpose for which the apparatus is used and can beregulated as desired by means of the cam-like devices 57 which operatethe control units 60. In a typical operation, the preheating timerequired may be 60 seconds, and the pressurizing and discharge time onlyseconds. With the double preheater described above, a puffed charge canbe delivered to the collector 15 every 30 seconds in automaticsuccession. All that is necessary is to keep the hopper 1 properlysupplied.

8 This is a continuation of U.S. application Serial No. 710,230 tiledJanuary 21, 1958, nOW abandoned for Vertical Gun-Pufiing Apparatus.

What is claimed is:

1. Cereal pufling apparatus comprising preheating means, a pressurizingchamber means beneath said preheating means, said two means beingarranged to provide a substantially vertical path of movement for thecereal charge from said preheating means into the top and out of thebottom of said chamber, said pressurizing chamber having a substantiallyuniformly cross-sectioned passage throughout its entire length, valvemeans controlling the passage of the charge from said preheating meansinto said chamber including an inlet valve closing the top of saidchamber, discharge valve means abutting the bottom of said chamber andhaving a passage therethrough which is in communication with and hassubstantial cross-section area relative to that portion of thepressurized chamber immediately adjacent thereto, said discharge valvemeans comprising an obturating valve in said passage and movable betweenan *obtiu'ating position and an open position in which said passage isunrestricted, whereby a cereal charge will be discharged from saidchamber with a nonthrottling action, power-operated actuating means foreach of said valve means, and timed power-control means for saidactuating means for operating said first valve means to pass the chargeby gravity into said chamber and close said inlet valve, and thenoperating said discharge valve means to cause the charge to escape fromthe bottom of said chamber.

2. Cereal pufiing apparatus :as defined in claim 1, including apressurizing fluid supply line connected with said chamber, and acontrol valve in said line having power-operated actuating meanscontrolled by said powercontrol means for admitting pressurizing fluidto said chamber in the interval between the successive operation of saidtwo valve means.

3. Cereal putting apparatus as defined in claim 2, said preheating meanshaving a warm air supply line, and a control valve in said warm airsupply line having poweroperated actuating means controlled by saidpower-control means for shutting off the supply of warm air to saidpreheating means when first valve means is operated to pass the cerealcharge into said chamber.

4. Cereal puffing apparatus as defined in claim 3, said power-operatedactuating means comprising a plurality of pneumatic cylinders one foreach valve to be operated, said power-contnol means comprising aplurality of pilot valves operated in timed sequence, each of said pilotvalves controlling the pneumatic fluid supply to one of said pneumaticcylinders.

5. Cereal pufiing apparatus comprising preheating means havingalternately discharge/able units and a pressurizing chamber meanslocated beneath said preheating means, said two means being arranged toprovide a substantially vertical path of movement for the cereal chargefrom said preheating means into the top of and out the bottom of saidchamber, said pressurizing chamber having a substantially uniformlycross-sectioned passage throughout its entire length, .a firstalternately operable valve means for discharging first one and then theother of said preheating units in alternation, a second inlet valvemeans at the top of said pressurizing chamber and a third dischargevalve means abutting the bottom of said pressurizing chamber and havinga passage therethrough which is in communication with and hassubstantial crosssection area relative to that portion of thepressurized chamber immediately adjacent thereto, said discharge valvemeans comprising an obturating valve in said passage and movable betweenan obturating position and an open position in which said passage isunrestricted, whereby a cereal charge will be discharged from saidchamber with a. non-throttling action, and timed valve-operating meansfor operating said three valve means in timed sequence to open saidfirst and second valve means and discharge the cereal charge by gravityfrom said preheating means into said pressurizing chamber, then to closesaid second valve means and hold the cereal charge in said pressurizingchamber, and then to open said third valve means and discharge thepufied cereal charge from said chamber.

6. Cereal pulling apparatus as defined in claim 5, including apressurizing fluid supply line connected to said chamber, and a fourthvalve controlling said supply line and operated by said valve-operatingmeans to open said supply line during the interval between closing saidsecnd valve means and opening said third valve means.

7. Cereal pufiing apparatus as defined in claim 6, said chamber beingapproximately tubular and said discharge valve means being movablebetween closed position and an open position in which the diameter ofthe open valve passage is at least a major fraction of the diameter ofthe chamber.

8. Cereal pufling apparatus as defined in claim 7, said yalve openingmeans comprising a powenactmated piston connected with said dischargevalve means and moving the discharge valve from closed position to fullyopen position on a single stroke of said piston.

9. Cereal pulling apparatus as defined in claim 5, said preheating meanscomprising spaced, substantially parallel and vertical walls defining apreheating zone between them, said walls being perforated tor thepassage of pre heating gas through said zone, the space between saidwalls at the bottom of said zone being open to provide a dischargeopening normally closed by said first valve means, and bottom wallsextending between said vertical walls on both sides of said opening,said bottom being inclined downwardly toward said opening at an angle tothe horizontal that is greater than the angle of repose of the preheatedcereal elements.

References Cited in the file of this patent UNITED STATES PATENTS

1. CEREAL PUFFING APPARATUS COMPRISING PREHEATING MEANS, A PRESSURIZINGCHAMBER MEANS BENEATH SAID PREHEATING MEANS, SAID TWO MEANS BEINGARRANGED TO PROVIDE A SUBSTANTAILLY VERTICAL PATH OF MOVEMENT FOR THECEREAL CHARGE FROM SAID PREHEATING MEANS INTO THE TOP AND OUT OF THEBOTTOM OF SAID CHAMBER, SAID PRESSURIZING CHAMBER HAVING A SUBSTANTIALLYUNIFORMLY CROSS-SECTIONED PASSAGE THROUGHOUT ITS ENTIRE LENGTH, VALVEMEANS CONTROLLING THE PASSAGE OF THE CHARGE FROM SAID PREHEATING MEANSINTO SAID CHAMBER INCLUDING AN INLET VALVE CLOSING THE TOP OF SAIDCHAMBER, DISCHARGE VALVE MEANS ABUTTING THE BOTTOM OF SAID CHAMBER ANDHAVING A PASSAGE THERETHROUGH WHICH IS IN COMMUNICATION WITH AND HASSUBSTANTIAL CROSS-SECTION AREA RELATIVE TO THAT PORTION OF THEPRESSURIZED CHAMBER IMMEDIATELY ADJACENT THERETO, SAID DISCHARGE VALVEMEANS COMPRISING AN OBTURATING VALVE IN SAID PASSAGE AND MOVABLE BETWEENAN OBTURATING POSITION AND AN OPEN POSITION IN WHICH SAID PASSAGE ISUNRESTRICTED, WHEREBY A CEREAL CHARGE WILL BE DISCHARGED FROM SAIDCHAMBER WITH A NONTHROTTLING ACTION, POWER-OPERATED ACTUATING MEANS FOREACH OF SAID VALVE MEANS, AND TIMED POWER-CONTROL MEANS FOR SAIDACTUATING MEANS FOR OPERATING SAID FIRST VALVE MEANS TO PASS THE CHARGEBY GRAVITY INTO SAID CHAMBER AND CLOSE SAID INLET VALVE, AND THENOPERATING SAID DISCHARGE VALVE MEANS TO CAUSE THE CHARGE TO ESCAPE FROMTHE BOTTOM OF SAID CHAMBER.